1. Field of the Invention
Preferred embodiments of the present invention generally relate to an image masking technique, and more particularly, to an image forming apparatus and an image forming method for efficiently masking image data using a unit formed of small-scale circuitry while maintaining image quality and reducing toner consumption.
2. Discussion of the Related Art
In general, in order to reduce toner consumption in image formation, a mask processing unit to mask image data is employed in an image forming apparatus. A conventional mask processing unit masks entire image data at one time or applies a large mask pattern to image data. As a result, several problems have arisen in that circuitry employed for masking is likely to increase in size, and image quality of a masked image deteriorates in comparison with an original image even if toner consumption is reduced by masking image data.
Several techniques have been proposed for masking image data efficiently. For example, a technique involving extracting several picture elements (pixels) in a predetermined relation between a pixel of interest and peripheral pixels from image data and using the extracted pixels for smoothing image data is conventionally known. In the technique, the several pixels are efficiently extracted from the image data by performing a logical operation on the image data in units of pixel matrices including a plurality of pixel arrays.
Alternatively, a technique for converting multivalic image data into small image data including less information than the multivalic image data by using characteristics of a density conversion curve is known. In the technique, a decrease in the number of graduations due to data conversion can be avoided, and a high quality image can be obtained.
However, the above-described techniques have a drawback in that several problems due to image processing still remain. According to the above-described techniques, an image forming apparatus is required to include large-scale circuitry. Furthermore, although toner consumption is reduced, original image quality is not maintained.